Ancient whale could be heaviest animal ever

The blue whale (Balaenoptera musculus) is no longer indisputably the heaviest animal to have ever lived. Fossilised vertebrae, ribs and part of a pelvis from a Perucetus colossus, dating from 38 million years ago, suggest that it was a whale of a whale, even though it is thought to have looked more like a manatee. Most blue whales weigh around 100–150 tonnes; the researchers’ best guess is that P. colossus weighed around 180 tonnes.